What sort of vertical and horizontal resolution can I get

Horizontal resolution depends on the data density. The instrument measures once per second, so at 3.6 km/hour (1 meter/sec) the data density is 1 reading/meter. At 1.8 km/hour it is 1 reading/50cm, and at 7.2 km/hour it is 1 reading/2 meters.

Vertical resolution depends on the separation between the centers of the receiver dipoles. At 2.5-m receiver-receiver separation vertical resolution is approximately 50 cm. At 5 meter separation it is 1 meter. Of course the ability to resolve a target depends on there being a resistivity contrast. Resolving a 10 Ohm-meter target in a 100 Ohm-m background is easier than resolving a 90 Ohm-m target in a 100 Ohm-m background. It is not possible to resolve a 100 Ohm-m target in a 100 Ohm-m background.

"The Geometrics G-882 is by far the best. On one job I did a few years ago, I was able to determine quarter gamma targets with the cesium magnetometer. From what I have seen this is the best magnetometer available bar none."